<!DOCTYPE html>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<script src="../resources/gesture-util.js"></script>
<style>
  body, html {
    width: 100%;
    height: 100%;
    margin: 0;
  }

  #rootscroller::-webkit-scrollbar {
    width: 0px;
    height: 0px;
  }

  #rootscroller {
    width: 100%;
    height: 100%;
    overflow: auto;
    position: absolute;
    left: 0;
    top: 0;
    background-color: red;
  }

  .spacer {
    width: 100%;
    height: 100%;
  }

  #fixed {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 80%;
    background-color: grey;
  }
</style>

<div id="rootscroller">
  <div class="spacer" style="background-color: PaleGreen"></div>
  <div class="spacer" style="background-color: Maroon"></div>
</div>

<div id="fixed">
  <p>
    To test, try scrolling over the grey region. The root scroller shouldn't be
    scrolled (you shouldn't see red appear).
  </p>
  <p>
    Try again while zoomed in, you should still be able to pan around
    (scrolling the visual viewport), but you should still not be able to scroll
    the red region into view.
  </p>
</div>

<script>
  if (window.internals) {
    internals.settings.setScrollAnimatorEnabled(false);
    internals.runtimeFlags.implicitRootScrollerEnabled = true;
  }

  async function runTest() {
    internals.setVisualViewportOffset(0, 0);
    rootscroller.scrollTop = 0;

    await waitForCompositorCommit();

    assert_equals(window.internals.effectiveRootScroller(document),
                  rootscroller,
                  "#rootscroller must be the effective root scroller");

    const delta = 3000;
    const location = { x: 5, y: 5 };
    await smoothScroll(delta,
                       location.x,
                       location.y,
                       GestureSourceType.TOUCH_INPUT,
                       'down',
                       SPEED_INSTANT);

    assert_equals(rootscroller.scrollTop,
                  0,
                  "RootScroller must not be scrolled");
  }

  window.onload = async () => {
    if (!window.internals)
      return;

    var rootscroller = document.querySelector('#rootscroller');

    promise_test( async t => {
      internals.setPageScaleFactor(1);
      await runTest();
    }, "Scrolling from fixed element while unzoomed.");

    promise_test( async t => {
      internals.setPageScaleFactor(2);
      await runTest();
      assert_greater_than(visualViewport.offsetTop,
                          0,
                          "Visual viewport must be scrolled");
    }, "Scrolling from fixed element while zoomed");
  }
</script>
